[dhalbert]

Idea by @dhalbert; change by Claude, after checking that the board builds don't use anything the mpy-cross job produces.

In build.yml, the ports job had needs: [scheduler, mpy-cross, tests], so no board build started until the mpy-cross job finished. But the scheduler job builds a separate mpy-cross for the ports jobs to use.

• Removed mpy-cross from the ports job's needs:. The final build-ci gate job still needs mpy-cross, so a run still fails if the mpy-cross job fails.

[dhalbert]

With this change, the graph is:

[mikeysklar]

Simple one-line change, and the right way to do it.

Checked the CI run: all 681 board builds started 2 minutes in, without waiting for mpy-cross.

The Windows mpy-cross build still took 97 minutes, which #11665 and #11667 address.